The present invention relates generally to a sockliner and more particularly to a sockliner which cushions a foot while preserving a cool and dry environment for the foot.
When walking and running, various portions of the foot impact the ground at different times during the gait cycle. Generally, an outside (i.e., lateral) portion of the heel strikes the ground first, and the foot pivots on the heel to bring the outside portion of the forefoot into contact with the ground. From this position, the foot rapidly rotates inwardly to a neutral position in which the bottom of the heel and the forefoot are in contact with the ground. Thus, certain parts of the foot are subjected to repeated impact forces during walking and running. Moreover, these impact forces transfer to related anatomical features such as the shins and knees. Over time, these forces can cause pain and injury to the structures and tissue of the feet and the related anatomical features.
Foam sockliners frequently are used in shoes to attenuate the impact forces applied to the feet by the ground during walking and running. In the past, these sockliners frequently were made of closed cell polyurethane foam which offered excellent shock attenuation properties and durability. However, when closed cell foam is compressed, it generates heat due to a phenomena known as hysteresis. Moreover, the closed cell foam does not breathe well because it is substantially impermeable to air. Thus, closed cell foam sockliners heat the foot and do not keep the foot dry.